US2009032706 (A1) describes a fast scanning probe microscope in which a detection beam is transmitted through scanning lenses and then reflected or scattered off the cantilever and received by a detector. A lens is translated by a scanner such that its motion is synchronous with that of the tip. In this way, the focused spot created by the lens tracks the moving cantilever. The use of a lens may cause problems due to chromatic aberration when illuminating the probe with light of different wavelengths. Also the lens may be heavy, making it difficult to move quickly and limit the speed of operation of the microscope.